As a result of the broad use of thin films across a wide variety of industrial applications, a tremendous amount of research has been conducted towards the development of thin film materials and methods for their manufacture in a cost effective manner. One example of such materials is small molecule organic semiconductors, which are currently under development for a number of applications, including displays, transistors and memories. U.S. Ser. No. 10/685,891, filed Oct. 14, 2003, the entire contents of which are hereby incorporated herein by this reference, describes a method and apparatus for depositing these materials in a high quality, low cost, manner with high throughput. In many of these applications, however, it desirable to provide not only a high quality, low cost, and high throughput deposition system, but also to provide a deposition system that provides these materials on a substrate in a predetermined pattern. For example, and not meant to be limiting, in display applications, it is highly desirable to deposit thousands, if not millions, of individual, discrete, uniform spots, termed pixels, each of which can be individually addressed by a controlling circuit. Unfortunately, such a system does not currently exist.
Conventional physical vapor deposition techniques or spin coating, although effective for small area, high value-added applications, are too slow to be cost effective for high throughput manufacturing, and further do not result in a patterned film. Organic vapor phase deposition using low vacuum and shower-head type geometries derived from the chemical vapor deposition industry have not been proven capable of the high deposition rates required for roll-to-roll fabrication. While printing techniques are amenable to pattern formation, they also tend to be too slow and generally restricted to batch manufacturing. Post-deposition patterning is difficult for organic materials due to incompatibility with photoresist chemicals, therefore most patterned organic thin films are made by depositing the film through a stencil mask in a batch process.
Other high speed deposition techniques include polymer multilayer deposition (PML), which is well-known for making uniform thin films of acrylate-based polymers. In general, the PML process has two forms evaporative and non-evaporative. Each begins by degassing the working monomer, which is a reactive organic liquid. In the evaporative process, the monomer is metered through an ultrasonic atomizer into a hot tube where it flash evaporates and exits through a nozzle as a monomer gas. The monomer gas then condenses on the substrate as a liquid film that is subsequently cross-linked to a solid polymer by exposure to UV radiation or an electron beam. In the non-evaporative process, the degassed liquid monomer is extruded through a slotted die orifice onto the substrate. It is then cross-linked in the same fashion as in the evaporative process. Salts, graphite or oxide powders, and other nonvolatile materials can be deposited in a homogeneous mixture with the monomer. Such mixtures cannot be flash evaporated, but are required for electrolyte, anode, cathode, and capacitor film layers. The evaporative process has been shown to produce thicknesses up to approximately 10 microns at speeds as great as 1000 feet per minute. The non-evaporative process have been shown to deposit thicknesses from 10 microns to about 50 mils at substrate speeds approaching several hundred feet per minute. Unfortunately, the polymeric materials amenable to PML deposition are electrically inert, and although it is possible to incorporate guest molecules into the PML flux, it is difficult to achieve a high enough loading of active material to create efficient semiconductors. A high throughput, continuous technique for small molecule semiconductors, combined with a patterning technique that also operates in a continuous manner, is thus needed to provide a viable route to high volume production of these non-polymeric materials, such as semiconductors, patterned on substrates.